diskimage-builder/diskimage_builder/elements/redhat-common/finalise.d/01-clean-old-kernels

#!/bin/bash

if [ ${DIB_DEBUG_TRACE:-0} -gt 0 ]; then
    set -x
fi
set -eu
set -o pipefail

if [ $DIB_DISABLE_KERNEL_CLEANUP -ne 0 ]; then
    echo "Skipping kernel cleanup as configured"
    exit 0
fi

YUM=${YUM:-yum}

if [[ ${YUM} == "dnf" ]]; then
    # cribbed from
    #  http://dnf.readthedocs.org/en/latest/cli_vs_yum.html
    _old_kernels="$(dnf repoquery --installonly --latest-limit=-1 -q)"
    if [[ -n "${_old_kernels}" ]]; then
        dnf remove -y ${_old_kernels}
    fi
else
    install-packages yum-utils
    package-cleanup --oldkernels -y --count=1
fi